When two user equipment terminals (e.g., mobile communication devices) of a cellular network or other telecommunication system communicate with each other, their data path typically goes through the operator network. The data path through the network may include base stations and/or gateways. If the devices are in close proximity with each other, their data path may be routed locally through a local base station.
It is also possible for two user equipment terminals in close proximity to each other to establish a direct link without the need to go through a base station. Telecommunications systems may use or enable device-to-device (“D2D”) communication, in which two or more user equipment terminals directly communicate with one another. In D2D communication, voice and data traffic (referred to herein as “communication signals”) from one user equipment terminal to one or more other user equipment terminals may not be communicated through a base station or other network control device of a telecommunication system.
Services that take advantage of D2D communication are referred to as proximity-based services (“ProSe) or D2D services. Such services typically include two phases: a discovery phase and a communication phase. The discovery phase involves the transmission and/or reception of discovery signals that allow user equipment terminals to detect when they are within proximity of each other. Proximity is determined when given proximity criteria are fulfilled. The communication phase involves the transmission and/or reception of communication signals directly between or among user equipment terminals. D2D services can also include other signaling phases involving signals such as sounding reference signals used to estimate the quality of communication channels, control signals used for establishing a communication channel, etc. The growing demand for increased speed, throughput, and efficiency in wireless communication networks requires continuing improvements in wireless communication processes, systems, and devices, including those related to D2D services and other D2D applications.
Prior solutions for control signaling between user equipment terminals of a telecommunication network involve a base station or other network control device of a telecommunication network generating or otherwise managing the control signaling. Depending on the level of control of the underlying telecommunication network (such as, but not limited to, an Evolved Universal Terrestrial Radio Access Network (“E-UTRAN”)) control signaling related to the D2D discovery and/or communication may be managed or generated by a base station or other network control device. Such prior solutions do not provide for user equipment terminals managing transmission power for signals used for D2D discovery and/or communication. Such prior solutions also do not provide for management of transmission power levels in multiple, overlapping networks in which D2D communication links can be instantiated.